1. Field of the Invention
The present invention relates to a thermal printer which forms an image by heating both surfaces of a print medium. More particularly, the present invention relates to a thermal printer which performs printing without being connected to a computer by mounting a memory card socket on a main board and is compact due to an optimal arrangement of the memory card socket on the main board.
2. Description of the Related Art
Thermal printers print an image on a thermal imaging print medium by applying heat to the print medium with a recording head. The print medium reveals an image of a selected color depending on the heating temperature and the period of time that heat is applied. Thermal print medium is different from paper, which is typically used as a print medium, and has a structure as illustrated in FIG. 1.
Referring to FIG. 1, the thermal print medium includes a transparent substrate 1. A first image forming layer 2, a spacer 3, a second image forming layer 4, and an upper protective layer 5 are sequentially stacked on an upper surface of the transparent substrate 1. A third image forming layer 6, a reflective layer 7, and a lower protective layer 8 are sequentially stacked on a lower surface of the transparent substrate 1.
The first, second, and third image forming layers 2, 4, and 6 represent different colors and comprise yellow, magenta, and cyan leuco dyes, respectively, and a developer. The spacer 3 separates the first and second image forming layers 2 and 4 and is transparent so that the colors produced in the first and second forming layers 2 and 4 can be viewed from the side of the upper protection layer 5 opposite to the second forming layer 4. The colors in the first, second, and third image forming layers 2, 4, and 6 respond to different heating temperatures and heating times.
To form an image on a print medium having such a structure, a conventional thermal printer has a structure as illustrated in FIG. 2. Referring to FIG. 2, the conventional thermal printer includes a transfer unit 10 for transferring a print medium M, first and second recording heads 21 and 25 disposed on both surfaces of the print medium, respectively, and first and second support units 31 and 35 disposed to face the first and second recording heads 21 and 25, respectively. The first and second recording heads 21 and 25 are electrically connected to a main board 40 to receive power and image data from the main board 40.
As described above, the conventional thermal printer forms a color image on the print medium M using the two fixed recording heads 21 and 25. In this case, the recording heads 21 and 25 can be easily connected to the main board 40 using cables 41 and connectors 45. However, the use of two recording heads 21 and 25 complicates the structure of the thermal printer and increases the manufacturing costs of the thermal printer.
Furthermore, thermal printers should be capable of being used not only as an output device for a computer, but also should be capable of being directly or indirectly connected to various types of apparatuses capable of providing image data, such as, digital cameras, portable digital assistants (PDAs), cellular phones with built-in digital cameras, and the like. The thermal printers should receive image data from these apparatuses and print an image corresponding to the image data. Moreover, the thermal printer should be compact so that it can be carried.
Accordingly, there is also a need for an improved, compact thermal printer which is capable of being connected to various types of apparatuses, and which is capable of forming an image on both surfaces of a print medium by using a single movable recording head.